The present invention relates generally to equipment used in oilfield and, more particularly, to a valve actuator and method of manufacturing thereof.
Various types of valves are used in oilfield well exploration, drilling, and production equipment. Valves are coupled to a pipeline and are typically used to shut off or turn on the flow of a fluid, such as a liquid, gas or both. Valves are typically either unidirectional or bi-directional.
A gate valve is a type of valve that includes a substantially rectangular-shaped gate that is moved by an operator in and out of the valve body to control the fluid. Gate valves generally comprise a valve body having a central axis aligned with inlet and outlet passages, and a space between the inlet and outlet passages in which a substantially rectangular slide or gate may be moved perpendicular to the central axis to open and close the valve. In the closed position, the gate surfaces typically seal against sealing rings which surround the fluid passage through the valve body.
Gate valves are used to control the flow of a variety of fluids. Often the fluid to be controlled by the gate valve is under pressure. In the petroleum industry, gate valves are used along pipeline at various locations. The operator used to move a valve gate in and out of the valve body may be manual or may be actuated hydraulically, pneumatically or electrically, for example. Hydraulic gate valve actuators may include fail-safe features, to cause the gate to be closed (fail safe closedxe2x80x94FSC) or open (fail safe openxe2x80x94FSO) if the valve fails.
Embodiments of the present invention achieve technical advantages as an actuator for a gate valve having a failsafe mechanism.
In one embodiment, disclosed is a hydraulic actuator for a gate valve, comprising an actuator housing having a top portion and a bottom portion, a stationary piston being fixedly coupled to the actuator housing top portion. The piston includes an exterior surface, a bottom surface, and an upper cap region having a side. A hollow cylinder is disposed within the actuator housing proximate the piston exterior surface, the cylinder including an exterior surface and an exterior upper region, the cylinder including a shoulder at the exterior upper region. A hydraulic pressure line is disposed within the stationary piston, the hydraulic line extending between the piston bottom surface and the piston cap region side. An operating stem is coupled to the cylinder, the operating stem being disposed within the actuator housing bottom portion, wherein the operating stem is controllably coupleable to a gate valve.
In another embodiment, disclosed is a hydraulic actuator for a gate valve, comprising an actuator housing, a stationary piston fixedly coupled to the actuator housing top portion, the piston having a hollow interior portion. A hollow cylinder is disposed within the actuator housing proximate the piston exterior surface, the cylinder including a shoulder at the exterior upper region. An operating stem is coupled to the cylinder, the operating stem being disposed within the actuator housing bottom portion, wherein the operating stem is controllably coupleable to a gate valve.
Further disclosed is an override mechanism for a hydraulic actuator having a stationary piston, the piston including a hollow interior portion and an upper cap portion, the piston upper cap portion fixedly coupled to an actuator housing, the actuator including a hollow moveable cylinder disposed proximate the piston exterior surface. The override mechanism comprises an override stem disposed within the piston interior portion, where the override stem abuts the cylinder.
Also disclosed is a method of manufacturing a hydraulic actuator for a gate valve.
Advantages of embodiments of the invention include providing an actuator design that is smaller and more light-weight than prior art actuators. A built-in manual override mechanism may be disposed within a stationary piston. The moveable cylinder may include a built-in quick disconnect mechanism. A visual indicator stem may be coupled to the cylinder. The hydraulic port enters the piston from the side, freeing the interior portion of the piston to house other components of embodiments of the invention.